Epidural analgesia in the latent phase of labor and the risk of cesarean delivery: a five-year randomized controlled trial.

BACKGROUND The optimal timing of epidural analgesia has been a controversial issue, and how early women can benefit from epidural analgesia is still debated. The objective of this trial was to test the hypothesis that patient-controlled epidural analgesia given at cervical dilation of 1.0 cm or more does not increase the risk of prolonged labor or Cesarean delivery. METHODS After institutional review board approval and patient consent, 12,793 nulliparous patients requesting neuraxial analgesia were enrolled and randomized to an early epidural (cervical dilation at least 1.0 cm) or delayed epidural (cervical dilation at least 4.0 cm) group. A 15-ml epidural analgesic mixture consisting of 0.125% (1.25 mg/ml) ropivacaine plus 0.3 microg/ml sufentanil was given in a single bolus, followed by patient-controlled pump with a 10-ml bolus without background infusion. Repeatable meperidine (25 mg) was prescribed as being the rescue analgesic to patients in the delayed epidural group. The primary outcome was the rate of Cesarean section. RESULTS The median diameters of cervical dilation were 1.6 cm and 5.1 cm in the early and delayed epidural groups, respectively (P < 0.0001). The duration of labor from analgesia request to vaginal delivery was equal in both groups (11.3 +/- 4.5 h for early epidural and 11.8 +/- 4.9 h for delayed epidural group women, P = 0.90). No statistically significant difference in the rate of Cesarean section was observed between the two groups on the intention-to-treat analysis (23.2% vs. 22.8% in the early and delayed epidural groups, respectively; P = 0.51). CONCLUSIONS Epidural analgesia in the latent phase of labor at cervical dilation of 1.0 cm or more does not prolong the progression of labor and does not increase the rate of Cesarean in nulliparous women compared with the delayed analgesia at the cervical dilation of 4.0 cm or more.